1. Technical Field of the Invention
The present invention relates to an AC generator (i.e., alternator) for vehicles, which is mounted, for example, in motor trucks, construction machines and agricultural machines.
2. Related Art
In recent years, manufacturers of passenger automobiles and motor trucks have made their continual efforts to improve the engines in order to comply with the emission regulations. This improvement thus tends to increase the ambient temperature of the components mounted on an engine. On the other hand, there is a yearly increasing demand for devices that ensure safety in travel, as well as increasing demand for additional power supplies and enhancement in in-vehicle amenity, which in turn has increased electrical loads applied to an alternating current (AC) generator (alternator) in a vehicle.
AC generators for vehicles can be divided into two types in terms of its brush structure. One is AC generators with brushes, which are mainly used for passenger automobiles. The other is known as brushless AC generators, which generally have a long life and are mainly used for motor trucks of long-distance and long-duration travel, as well as construction and agricultural machines obliged to work in adverse environments with swirling dust. Such a brushless AC generator is disclosed, for example, in Japanese Patent Laid-open Publication No. 2002-095215.
Generally, markets and users require that components of such AC generators can be changed without special tools. Specifically, such components as a rear cover, a housing, a rectifier, field windings, a rotor, a stator, bearings are demanded to be fixed with screws so that attachment/detachment can be facilitated when, for example, these components are changed. Briefly, AC generators having good service performance are demanded to be manufactured.
Japanese Patent Laid-Open Publication No. 2003-169457, for example, discloses an AC generator for vehicles, in which the stator windings and the rectifier are fixedly screwed to establish electrical connection. However, in a brushless AC generator, the side wall of the rear housing may often be axially extended toward the rear cover, in order to prevent damage to the electrical components, such as the rectifier and the regulator, which damages are caused by external forces induced by pebbles or the like in the working area. In this case, if the side wall interferes with the screwing position of the rectifier, the fixation with a screw will be physically impossible.
Japanese Patent Laid-Open Publication Nos. 2002-095215 and 2005-176423, for example, disclose another vehicular AC generator. According to these literatures, each lead of the stator windings is caulked to a portion in the rear housing, which is near the surface where the rectifier is attached, and then soldered or welded for fixation. As mentioned above, in the case where the side wall of the rear housing is axially extended toward the rear cover, welding or soldering for fixation of the leads may impair the service performance of the AC generator because of the presence of the side wall of the rear housing.
Accordingly, in order to electrically connect the leads of the stator windings and the rectifier in consideration of the service performance, the best approach may be to set a fixedly screwing position at a position higher than the side wall of the rear housing. However, the change in the screwing position of each lead of the stator windings may cause, in turn, another problem of increasing the length of the lead.
A rectifier of the AC generator has a plus-side (positive electrode side) radiating fin and a minus-side (negative electrode side) radiating fin, to each of which a plurality of rectifying elements are attached. If cooling air is directly blown to the sealed portion of each of the rectifying elements, an electrically conductive liquid containing a snow melting agent, for example, is very likely to be directly in contact with the sealed portion, which will create undesirable conditions as far as the environmental resistance is concerned. Creation of such undesirable conditions may be prevented by directing each lead, which is drawn from the sealed portion of the rectifying element, to the direction opposite to the rear cover. However, this may necessarily permit metal terminals (metallic terminals) on a terminal mount (terminal table) to be located on the side of the rear housing, which metal terminals are to be electrically connected to the respective leads of the rectifying elements. Accordingly, the terminal mount included in the rectifier may mostly be located at a position closest to the rear housing. Thus, the terminal mount is formed with a plurality of L-shaped supports (L-shaped legs), each axially extending from a surface of the rear housing, on which the rectifier is mounted, and extending toward the rear cover, with a fixedly screwing portion being provided at its end for establishing electrical connection with each lead of the stator windings.
However, there is a long distance between the fixedly screwing portion provided at the end of each L-shaped support and the base portion of the L-shaped support on the side of the rear housing. Therefore, in fixedly conducting screwing, bending stress will be imposed on the L-shaped support of the terminal mount. Thus, problematically excessive bending stress of assemblage has been caused at the base portion of each lead of the stator windings, as well as the caulked portion between the lead and the metal terminal attached to the end of the lead.
One approach for reducing the bending stress may be to mechanically fix the vicinity of the fixedly screwing portions of the terminal mount against the radiating fin, fixing with a screw or ultrasonic welding. Another approach may be to replace each lead of the stator windings with a stranded wire. However, these approaches may involve high manufacturing cost and high component cost. Thus, if emphasis is put on reducing the costs, these approaches are difficult to be employed.